Account payable and receivable

Hi,

My current client took over another company and need to migrate them in to SAP existing company code. I am looking after AR, AA and AP.

I have following concerns:

Business need is to have historical data for last 2 years for both AR and AP and their payments details for duplicate check from others company legacy system to the parent company.

we normally migrate only open items but here the need is to upload old cleared invoiced along with payment details.

I need assistance for this how to proceed.

Further there is use of some electronic media like Ariba even that invoice need to picked up for AP and Siebal CRM data for AR.

Its very critical. Points will be awarded.

Bay

AC